Openvpn

OpenVPN is an open source software application for VPN tunneling. It's one of the safest in the world. OpenVPN differs from other VPN protocols in the way that it requires a separate client program to connect to the server.

OpenVPN on avoimella lähdekoodilla toimiva VPN. Tämä on yksi maailman turvallisimmista VPN protokollista. OpenVPN eroaa muista VPN protokollista, että vaatii erillisen asiakasohjelman muodostaakseen yhteyden palvelimeen.

Asennus

Asenna OpenVPN paketti pakettihallinnasta palvelin ja asiakaslaitteille. Windowssille löytyy erillinen paketti täältä.

 aptitude install openvpn

Konfigurointi

Sertifikaatit

Asennuksen jälkeen sinun tulee kopioida oletushakemistosta tiedostoja jotta palvelin voi lukea niitä

 cp -r /usr/share/doc/openvpn/examples/easy-rsa /etc/openvpn

Tämän jälkeen siirrytään generoimaan RSA avaimet VPN palvelua varten.

 cd /etc/openvpn/easy-rsa/2.0/

Muokkaa tämän jälkeen vars tiedostoa

 nano /etc/openvpn/easy-rsa/2.0/vars

vars - tiedostossa muuta export KEY_SIZE 1024 -> 2048

# Increase this to 2048 if you
# are paranoid.  This will slow
# down TLS negotiation performance
# as well as the one-time DH parms
# generation process.
export KEY_SIZE=2048

Voit halutessasi kirjoittaa valmiiksi konfiguroinnit tähän tiedostoon.

Tallenna ja sulje tiedosto sekä käynnistä openvpn palvelu uudelleen

 service openvpn restart

Määritetään konfigurointitiedosto ./vars ja tyhjennetään vanhat avaimet

 source ./vars

 ./clean-all

Root sertifikaatti

Luodaan root sertifikaatti

 ./build-ca

Tämän jälkeen vastaa ohjattuun velhoon:

Generating a 2048 bit RSA private key
..+++
..................................................+++
writing new private key to 'ca.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [US]:FI
State or Province Name (full name) [CA]:Lounais-Suomi
Locality Name (eg, city) [SanFrancisco]:Turku
Organization Name (eg, company) [Fort-Funston]:Taistowiki
Organizational Unit Name (eg, section) [changeme]:Labs
Common Name (eg, your name or your server's hostname) [changeme]:vpn.taisto.org
Name [changeme]:Taistowiki VPN
Email Address [[email protected]]:[email protected]

Palvelin sertifikaatti

Sertifikaatin genroimisen jälkeen luodaan privaattiavain palvelimelle. Muuta vpn.taisto.org vastaamaan palvelimesi nimeä.

 ../build-key-server vpn.taisto.org

Tämän jälkeen vastaa jälleen seuraa velhoa

Generating a 2048 bit RSA private key
.................................................+++
.............................................................+++
writing new private key to 'vpn.taisto.org.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [US]:FI
State or Province Name (full name) [CA]:Lounais-Suomi
Locality Name (eg, city) [SanFrancisco]:Turku
Organization Name (eg, company) [Fort-Funston]:Taistowiki
Organizational Unit Name (eg, section) [changeme]:Labs
Common Name (eg, your name or your server's hostname) [vpn.taisto.org]:
Name [changeme]:Taistowiki
Email Address [[email protected]]:[email protected]

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Using configuration from /etc/openvpn/easy-rsa/2.0/openssl-1.0.0.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName           :PRINTABLE:'FI'
stateOrProvinceName   :PRINTABLE:'Lounais-Suomi'
localityName          :PRINTABLE:'Turku'
organizationName      :PRINTABLE:'Taistowiki'
organizationalUnitName:PRINTABLE:'Labs'
commonName            :PRINTABLE:'vpn.taisto.org'
name                  :PRINTABLE:'Taistowiki'
emailAddress          :IA5STRING:'[email protected]'
Certificate is to be certified until Aug 15 12:00:08 2025 GMT (3650 days)
Sign the certificate? [y/n]:y


1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated

Generoi Diffie Helman key exhange parametri. Tässä menee hetki.

 ./build-dh

Asiakas sertifikaatti

Nyt luodaan OpenVPN asiakkaille sertifikaatti. Jokaisella asiakkaalla tulee olla oma sertifikaatti. Muuta client vastaamaan asiakkaan isäntänimeä.

 ./build-key client

Generating a 2048 bit RSA private key
...................................................................................+++
............+++
writing new private key to 'client.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [US]:FI
State or Province Name (full name) [CA]:Lounais-Suomi
Locality Name (eg, city) [SanFrancisco]:Turku
Organization Name (eg, company) [Fort-Funston]:Taistowiki
Organizational Unit Name (eg, section) [changeme]:Labs client
Common Name (eg, your name or your server's hostname) [client]:
Name [changeme]:Taistowiki
Email Address [[email protected]]:[email protected]

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Using configuration from /etc/openvpn/easy-rsa/2.0/openssl-1.0.0.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName           :PRINTABLE:'FI'
stateOrProvinceName   :T61STRING:'\0xFFFFFFC3Lounais-Suomi'
localityName          :PRINTABLE:'Turku'
organizationName      :PRINTABLE:'Taistowiki'
organizationalUnitName:PRINTABLE:'Labs client'
commonName            :PRINTABLE:'client'
name                  :PRINTABLE:'Taistowiki'
emailAddress          :IA5STRING:'[email protected]'
Certificate is to be certified until Aug 15 12:05:36 2025 GMT (3650 days)
Sign the certificate? [y/n]:y


1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated

Kopioi Root, palvelin sekä DH param sertifikaatti tiedostot OpenVPN root hakemistoon:

cp /etc/openvpn/easy-rsa/2.0/keys/ca.crt /etc/openvpn
cp /etc/openvpn/easy-rsa/2.0/keys/ca.key /etc/openvpn
cp /etc/openvpn/easy-rsa/2.0/keys/dh2048.pem /etc/openvpn
cp /etc/openvpn/easy-rsa/2.0/keys/server.crt /etc/openvpn
cp /etc/openvpn/easy-rsa/2.0/keys/server.key /etc/openvpn

Kumoa sertifikaatti

Seuraavilla komennoilla voit kumota käyttäoikeuden palvelimeen. Muuta client1 nimeä asiakasnimeksi minkä oikeuden haluat peruuttaa.

 . /etc/openvpn/easy-rsa/2.0/vars
 . /etc/openvpn/easy-rsa/2.0/revoke-full client1

Palvelimen konfigurointi

Pura ZIP tiedosto

 gunzip -d /usr/share/doc/openvpn/examples/sample-config-files/server.conf.gz

Kopioi esimerkki palvelin konfigurointi tiedosto /etc/openvpn hakemistoon

 cp /usr/share/doc/openvpn/examples/sample-config-files/server.conf /etc/openvpn

Sinun tulee vielä muokata server.conf tiedostossa muutama kohta ennen kuin voidaan ottaa OpenVPN palvelin käyttöön:

 nano /etc/openvpn/server.conf

• Oikeat avain tiedostot ja niiden polku

# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key).  Each client
# and the server must have their own cert and
# key file.  The server and all clients will
# use the same ca file.
#
# See the "easy-rsa" directory for a series
# of scripts for generating RSA certificates
# and private keys.  Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see "pkcs12" directive in man page).
ca ca.crt
cert server.crt
key server.key  # This file should be kept secret

# Diffie hellman parameters.
# Generate your own with:
#   openssl dhparam -out dh1024.pem 1024
# Substitute 2048 for 1024 if you are using
# 2048 bit keys.
dh dh2028.pem

Lopuksi käynnistä VPN palvelu uudelleen

 service openvpn restart

Asiakkaan konfigurointi

Kopioi OpenVPN palvelimelta client.conf tiedosto omaan kotihakemistoon ja siirrä omalle asiakaslaitteelle

 cp /usr/share/doc/openvpn/examples/sample-config-files/client.conf ~/

Kopioi lisäksi ca (ca.crt) ja client sertifikaatit (client.crt) sekä privaattiavain (client.key) asiakaslaitteelle.

Avaa client.conf tiedosto

nano ~/client.conf

Muokkaa tämä tiedosto seuraavanlaiseksi:

• Määritä OpenVPN palvelimen osoite sekä portti, oletus 1194

# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
remote my-server-1 1194
;remote my-server-2 1194

• Määritä sertifikaattien polku

# SSL/TLS parms.
# See the server config file for more
# description.  It's best to use
# a separate .crt/.key file pair
# for each client.  A single ca
# file can be used for all clients.
ca ca.crt
cert client.crt
key client.key